In January 1980, when Wings flew to Tokyo for a tour of Japan, customs officials found approximately 8 ounces of cannabis in Paul McCartney’s luggage. They arrested McCartney and brought him to a local jail while the Japanese government decided what to do. After ten days, they released and deported him without charge. A couple of busts since then, in 1997, he spoke out in support of decriminalisation of the drug: “People are smoking pot anyway and to make them criminals is wrong.” He did however, decide to quit cannabis in 2015, citing a desire to set a good example for his grandchildren.
Here’s a news report from that time Paul McCartney was busted in Japan back in 1980.